JP2005095729A - Treatment method and treatment apparatus for organic type waste containing biodegradable plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating an organic type waste containing biodegradable plastics using an excellent recycle technology with a compact apparatus that effects a high productivity and advantages in securing a site therefor, which comprises decomposing and fermenting the organic type waste containing the biodegradable plastics intermingled therewith to recover methane gas efficiently in a short term by utilizing the methane fermentation technology. <P>SOLUTION: The method for treating the organic type waste containing the biodegradable plastics comprises a hydrolysis step of performing the hydrolysis in a hydrolysis tank 21 by adding a diluted water 25 to inflammable refuse 1 as the organic type waste intermingled with the biodegradable plastics, a methane fermentation step of performing the methane fermentation of the hydrolyzed decomposed product 23 under anaerobic conditions using a methane fermentation tank 6 and a recovery step of recovering the methane gas 7 produced by the fermentation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for treating organic waste, and particularly relates to a useful treatment technique for realizing recycling of organic waste containing biodegradable plastics.

  Garbage, firewood, food waste, woody waste such as pruned branches and waste wood, and organic waste such as paper are generally incinerated as combustible waste. The problem that carbon dioxide and dioxin in exhaust gas give to the air environment has surfaced, and the situation is that stricter emission regulations are being added. While technological development and practical application such as combustion technology for minimizing the emission of these harmful gases are being promoted, the above problems will be solved at once by recycling (recycling) organic waste. New movements are becoming active. The use of methane fermentation technology is attracting attention as a means to realize recycling of organic waste.

  A conventional organic waste recycling process using this methane fermentation technology is shown in the process schematic diagram of FIG. The outline of this technology will be explained. First, combustible garbage 1 containing organic waste that has been collected is broken and crushed, and then applied to a separator 2 to be fermentable material 3 made of organic waste and a garbage bag. They are separated into unsuitable fermentation 4 made of plastics, metals, etc., and unsuitable fermentation is discharged out of the system as waste. The fermentable material 3 that has been crushed is sent to the adjustment tank 5 where it is temporarily stocked. Subsequently, a certain amount of the fermentable material 3 is taken out from the adjustment tank 5 and put into the fermentation tank 6. In this fermenter 6, methane fermentation of the fermentable material 3 is promoted by anaerobic microorganisms under anaerobic conditions. And the methane gas 7 produced | generated by methane fermentation is collect | recovered from the fermenter 6, and the digest 8 which finished fermentation is discharged | emitted from the fermenter 6. FIG. Thereafter, the digested product 8 is sent to a dehydrator 9 and dehydrated, separated into a dehydrated residue 10 and a dehydrated filtrate 11 and discharged out of the system. The dehydrated filtrate 11 is purified by a subsequent wastewater treatment process, and unsuitable fermentation materials and dehydrated residues are generally treated by incineration.

  In addition, in order to further accelerate the reaction in the fermenter 6, a technique has been proposed in which the fermentable material 3 is fluidized at a high pressure and high temperature using a separate reactor in advance (Patent Document 1, etc.).

  By adopting such methane fermentation technology, most organic waste is converted into methane gas as clean fuel without being incinerated and recycled as useful resources.

  By the way, combustible waste containing organic waste is often mixed with plastic materials such as garbage bags and plastic products as described above. Recently, some of these plastic materials still contain small amounts of biodegradable plastic. This is because, in the field of plastics, there is a demand for the use of an environmentally friendly polymer material that accurately responds to environmental problems, and biodegradable plastics are being put into practical use as an optimum material that can respond to this.

  This biodegradable plastic maintains its performance during the period of use, and after use it is decomposed by microorganisms such as bacteria in the natural environment (such as in the ground) and eventually becomes carbon dioxide and water, which is an environmental load. It has excellent environmental suitability not found in ordinary plastics. For this reason, biodegradable plastics are still at a cost disadvantage, but resource materials for agriculture, forestry and fisheries (multi-films, seedling pots, fish nets, etc.), civil engineering and construction materials (insulation materials, formwork, water retention sheets, etc.) And food packaging supplies (fresh food trays, fast food / instant food containers, etc.), sanitary goods (paper diapers, etc.), and various daily and miscellaneous goods such as garbage bags, drainers, cups, etc., are gradually being used. It is expected to be used in many fields and products in the future.

  Therefore, assuming that this biodegradable plastic is produced and used in earnest, it may be a product that is supposed to be used in a natural environment, but it may be used in various other fields. In this case, a large amount of waste after use is generated, and as a result, it is expected that the waste will be mixed with combustible waste together with organic waste. Moreover, although biodegradable plastics have the above environmental suitability, they are mixed with ordinary plastics that are difficult to decompose, and separation of both is not easy, so these are buried together in the ground, It cannot be processed.

  In the conventional technology using the methane fermentation technology described above, biodegradable plastics are finally incinerated as fermentation unsuitables 4 like other plastics, and their recycling is completely taken into consideration. Absent. Therefore, although organic wastes are recycled, biodegradable plastics still have the problem of environmental burden from the viewpoint of carbon dioxide generation and dioxin generation by incineration.

  Recently, biodegradable plastic garbage bags made mainly of polyester resin have begun to be used. However, the conventional technology collects combustible garbage (including organic waste). The used biodegradable plastic garbage bags are also separated as fermentation unsuitables 4 by pretreatment. As a result, a large amount of waste derived from garbage bags is generated (because the bulk density is small and bulky), and the treatment is also often carried out by incineration, so that the load on the environment is large from the same viewpoint. Furthermore, in the case of this prior art, there exists a problem that the fragment | piece of the garbage bag which could not be separated would accumulate in the subsequent fermentation tank 6, and reduce an effective methane fermentation volume. In addition, it may become entangled with the agitation drive section of the fermenter 6 and the slurry transfer pump, causing mechanical troubles and causing clogging of the piping.

  On the other hand, considering that organic waste mixed with biodegradable plastic is conscious, the organic waste is heat-treated at 60 to 100 ° C. for 1 to 48 hours to collapse the biodegradable plastic in the waste. Then, a technique for composting has been proposed (Patent Document 2 and the like). This technology is useful in the sense that it is finally composted including biodegradable plastics and recycled as fertilizer and soil conditioner.

However, because this conventional technology is intended for composting, heat treatment for biodegradable plastic decomposition is a low temperature and long-time condition, and in this pretreatment, the plastic decomposition is at most about half. It only progresses to molecular weight. Moreover, composting under post-treatment aerobic conditions requires a fermentation period of several months, and a huge apparatus and a large site are required for this fermentation. Furthermore, in Japan, the amount used is very small compared to the amount actually discharged, and in addition, the cost of transportation and the like is high, so it is difficult to say that this is an effective recycling method. In addition, clean energy such as methane gas cannot be recovered and used, so it must be said that the recycling technology is still insufficient.
JP-A-8-99099 JP 2001-269652 A

  The present invention has been made in view of the above technical background and the problems of the prior art, and uses organic waste containing biodegradable plastics by using methane fermentation technology to replace biodegradable plastics. In order to provide excellent recycling technology that can be realized by a compact device that can efficiently decompose and ferment in a short period of time and recover methane gas by recovering methane gas and that is advantageous for securing the site. It is a subject.

In order to achieve the above-mentioned problems, the present invention proposes the following features of the invention regarding the recycling technology of organic waste containing biodegradable plastic.
(1) Hydrolysis process in which diluted water is added to organic waste containing biodegradable plastics for hydrolysis, and methane fermentation process in which hydrolyzed decomposition products are subjected to methane fermentation under anaerobic conditions And a recovery step of recovering the methane gas generated by the fermentation, and a method for treating organic waste containing biodegradable plastic (claim 1).
(2) Organic waste containing biodegradable plastics is separated into fermentable materials and unsuitable fermentation materials containing biodegradable plastics, and hydrolysis is performed by adding dilution water to the unsuitable fermentation materials. A hydrolysis process for performing fermentation, a methane fermentation process for performing methane fermentation of the fermentation suitability product and the hydrolyzed degradation product under anaerobic conditions, and a recovery process for recovering methane gas generated by the fermentation. A method for treating organic waste containing biodegradable plastics (Claim 2).
(3) The biodegradable plastic according to the above (1) or (2), which comprises each step after the hydrolysis step and a separation step for separating unsuitable fermentation products from the hydrolyzed decomposition product. (Claim 3) A method for treating organic waste containing
(4) Prior to the methane fermentation step, (1) to (1) comprising the steps of adjusting the concentration of the hydrolyzed decomposition product and / or the fermentable material into the methane fermentation step. A method for treating organic waste containing the biodegradable plastic according to any one of (3) (Claim 4).
(5) The method for treating organic waste containing the biodegradable plastic according to any one of (1) to (4), wherein the biodegradable plastic is used as a container for organic waste. (Claim 5).
(6) The organic waste processing method including the biodegradable plastic according to (5), wherein the organic waste container is made of a polyester resin material (Claim 6).
(7) A method for treating organic waste containing the biodegradable plastic according to any one of (1) to (4), wherein the biodegradable plastic is used as a food packaging container (claim). 7).
(8) The processing method of the organic waste containing the biodegradable plastic in any one of said (1)-(7) whose temperature of the said hydrolysis process is 120 to 250 degreeC (Claim 8).
(9) The processing method of the organic waste containing the biodegradable plastic according to any one of (1) to (8), wherein the treatment time of the hydrolysis step is 5 minutes to 60 minutes. ).
(10) The addition according to any one of (1) to (9), wherein addition of dilution water to the unsuitable fermentation product in the hydrolysis step is performed such that the solid content is 50% or less. A method for treating organic waste containing biodegradable plastics (claim 10).
(11) Organic waste containing the biodegradable plastic according to any one of (1) to (10), wherein a dehydrated separation liquid obtained from the methane fermentation step is used as the dilution water in the hydrolysis step. A method for processing an object (claim 11).
(12) Separation means for separating organic waste mixed with biodegradable plastic into fermentable material and unsuitable fermented material containing biodegradable plastic, and hydrolysis is performed by adding dilution water to the unsuitable fermented material. Methane that performs methane fermentation under anaerobic conditions between hydrolysis means, separation means for separating unsuitable fermentation residue from the hydrolyzed decomposition product, and fermentation suitability and hydrolyzed decomposition product An organic waste processing apparatus comprising a biodegradable plastic, comprising: fermentation means; and recovery means for recovering methane gas generated by the fermentation.

According to the present invention having such characteristics, the advantageous effects listed below can be obtained.
(1) Effective recycling (process) can be easily realized for the treatment of various types of waste composed of organic waste mixed with biodegradable plastics.
(2) Especially in the case of garbage bags made of biodegradable plastic used for garbage collection, troubles in the fermenter, its peripheral equipment, and piping systems, which have been problematic in the past, are resolved and reduced. Tonality can also be done effectively.
(3) Since it is an efficient and simple process, it requires relatively few devices and equipment, requires only a small scale, is advantageous in securing land, and is easy to put into practical use as a whole. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a process outline diagram showing an organic waste recycling process according to an exemplary embodiment of the present invention.

  First of all, the combustible waste 1 collected here and stored in a garbage bag made of biodegradable plastic includes plastics, metals and the like together with various organic wastes. It is assumed that biodegradable plastics are mixed in plastics.

  The biodegradable plastic here refers to polysaccharides such as amylose, dextran, alginic acid, chitin, chitosan, cellulose, starch, pullulan, polyglycolic acid, poly-3-hydroxypropionate, polylactic acid, poly-3. -Hydroxybutyrate, poly-4-hydroxybutyrate, polyhydroxyvalylate, polycaprolactone, polyethylene succinate, polybutylene succinate, polybutylene adipate, polybutylene succinate / adipate, polybutylene adipate / terephthalate, polybutylene succinate Polyester resins such as nate / terephthalate, polybutylene succinate / adipate / terephthalate, polytetramethylene adipate / terephthalate, polyvinyl alcohol, polypeptides, etc. But it is under, biodegradable plastic garbage bag there are many things that mainly composed mainly of polyester resin.

  The combustible waste 1 is broken and crushed in the same manner as before, and then sent to the sorter 2 to be fermentable 3 made of organic waste and unsuitable for fermentation 4 made of garbage bags, plastics, metals, etc. (Sorting process). The fermentable material 3 is sent to the adjustment tank 5 and stocked, where the concentration charged into the next methane fermentation tank 6 is adjusted (adjustment process). In this adjustment tank 5, acid fermentation proceeds while being stocked.

  On the other hand, the unsuitable fermentation 4 is sent to the hydrolysis device 21, where water (diluted water) is added, and the biodegradable plastic (garbage bag and part of the plastic) is hydrolyzed (hydrolysis step). ). The conditions in this hydrolysis step are carried out at a temperature of 120 ° C. to 250 ° C., preferably 150 ° C. to 180 ° C., for 5 to 60 minutes, with a vapor pressure at each temperature. Moreover, the addition amount of dilution water is performed so that the solid content of the fermentation unsuitable 4 may be 50% or less. As the dilution water 25, the dehydrated filtrate 11 obtained from the dehydrator 9 in the subsequent process is used.

  The fermentation unsuitable 4 that has been hydrolyzed in this way is sent to the screen 22, and is decomposed and produced with a low molecular weight mainly composed of monomers and oligomers such as organic acids, alcohols, and sugars produced by the decomposition reaction of the biodegradable plastic. The product 23 is mechanically separated into a normal plastic and a non-decomposed product 24 such as metal (separation process). Non-decomposed matter 24 is discharged out of the system.

Next, the decomposition product 23 that has become a form that is easily fermented by hydrolysis is supplied to the methane fermentation tank 6 together with the fermentable material 3 stocked in the adjustment tank 5, where microorganisms (methane methane) are analyzed under anaerobic conditions. ) To perform methane fermentation (methane fermentation process). This methane fermentation is completed in about two weeks, and the methane gas generated by the fermentation is sequentially recovered from the fermenter 6 and stored in a gas holder (not shown) (recovery step). In this way, the recovered methane gas is used as clean fuel energy.
The digest 8 produced by this fermentation is taken out from the fermenter 6 and then sent to a dehydrator 9 where it is separated into a dehydrated residue 10 and a dehydrated filtrate 11. The dehydrated residue 10 is then composted and used as a fertilizer or landfilled or incinerated. As described above, the dehydrated filtrate 11 is sent to the hydrolysis step and circulated and used as the dilution water 25. When this dehydrated separation liquid is hydrolyzed as a diluent, ammonia is removed by evaporation, and the ammonia concentration in the return diluted water is lowered. As a result, the ammonia concentration in the methane fermentation tank 6 is also reduced, leading to stabilization of methane fermentation.

  In the present embodiment, biodegradable plastics, ordinary plastics, and metals are not particularly separated and are supplied to the hydrolysis apparatus together as unsuitable fermentation materials. It is also possible to separate only the plastics and hydrolyze only the plastics, thereby reducing the load on the hydrolysis apparatus. If the biodegradable plastic and the normal plastic can be separated, it is of course possible to hydrolyze only the biodegradable plastic. In this case, the load on the apparatus during hydrolysis can be further reduced. Furthermore, when the biodegradable plastic has already been separated in the garbage collection stage, it can be crushed and supplied as it is to the hydrolysis device, so that the separation process becomes unnecessary, and the load on the device is minimized. This is the best mode.

  In the present embodiment, the dilution water used in the hydrolysis step uses the dehydrated filtrate of digested material after fermentation, but other water such as irrigation water may be used.

  Next, FIG. 2 is a process outline diagram showing an organic waste recycling process according to another embodiment of the present invention.

  First of all, the combustible waste 1 collected here is stored in a biodegradable plastic garbage bag, and all the collected garbage is made of organic waste, such as plastics and metal. Etc. are not substantially included in this.

The combustible waste 1 containing organic waste is broken and crushed, and then sent to the hydrolysis device 21 without being separated. Water (diluted water) is added in the hydrolysis device 21 to hydrolyze the biodegradable plastic (trash bag) and organic waste (hydrolysis step). The conditions in this hydrolysis step are the same as in the above-described embodiment, and are carried out at a temperature of 120 ° C. to 250 ° C. (preferably 150 ° C. to 180 ° C.) at a vapor pressure at each temperature for 5 to 60 minutes. Similarly, the amount of dilution water added is such that the solid content of the combustible waste 1 is 50% or less. Diluted water 25 uses dehydrated filtrate 11 obtained from the dehydrator 9 in the subsequent process. By this hydrolysis process, almost all biodegradable plastics (trash bags) are monomers and oligomers such as organic acids, alcohols and sugars. Is a low-molecular-weight decomposition product 23 mainly composed of, which is easily fermented and discharged out of the apparatus.

  The total amount of these decomposition products 23 is sent to the adjustment tank 5 and stocked, and the input amount to the methane fermentation tank 6 is adjusted here (adjustment process). Moreover, in the adjustment tank 5, acid fermentation advances.

  Next, the degradable organisms in the adjustment tank 5 are taken out as appropriate, and a necessary amount is charged into the methane fermentation tank 6 so that the fermented product has a predetermined concentration. And in this fermenter 6, like the said embodiment, methane fermentation is made | formed by microorganisms (methane bacterium) under anaerobic conditions (methane fermentation process), this methane fermentation is completed in about two weeks, and the methane gas generated by fermentation 7 is sequentially recovered from the fermenter 6 and stored in a gas holder (not shown) (recovery step). In this way, the recovered methane gas is used as clean fuel energy.

  The digest 8 produced by this fermentation is taken out from the fermenter 6 and then sent to the dehydrator 9 where it is separated into a dehydrated residue 10 and a dehydrated filtrate 11. The dehydrated residue 10 is then composted and used as a fertilizer or landfilled or incinerated.

  According to the present embodiment, compared to the process of the previous embodiment, the separation and separation steps of unsuitable fermentation products and non-degradable products before and after the hydrolysis step can be omitted, and unsuitable fermentation materials other than biodegradable plastics (usually normal) It is made up of organic waste and biodegradable plastics because the process efficiency is excellent and the equipment and equipment can be simplified. It is recommended as an extremely effective recycling process for combustible waste.

In both of the above-described embodiments, the case where an amorphous garbage bag made of biodegradable plastic is used as a container used for collecting and collecting organic waste has been described. Needless to say, it may be a container that has been used as a regular container.
Hereinafter, in order to demonstrate the advantageous effects of the present invention, description will be given by giving experimental examples focusing on the process conditions in the hydrolysis step employed by the present invention.
(Example 1)
First, the results of experiments and examinations on the relationship between the treatment time using a bag of polylactic acid material, which is a biodegradable plastic, and the hydrolysis effect will be described. A bag made of the target polylactic acid material suspended in distilled water at 10 g / L was kept in a high-temperature thermostatic bath for a predetermined time, and then placed in water at room temperature to rapidly cool the treatment time. Moreover, the hydrolysis effect was represented by the reduction rate of solid content (SS; Suspended Solids) before and after the heat treatment. The measuring method was measured according to the sewer test method (supervised by the Ministry of Construction and the Ministry of Health and Welfare, 1997 edition).

  FIG. 3 shows the relationship between the processing time and the solid content reduction rate according to the experimental results. From this figure, it can be seen that 50% solids weight is reduced by hydrolysis for 3 minutes, 70% is reduced by treatment for 5 minutes, and 98% solids is reduced by treatment for 10 minutes. On the other hand, it is known that the solid content reduction amount is almost constant at around 95% in the treatment time of 10 minutes or more, and the solid content reduction amount is conversely lowered after 60 minutes. Furthermore, as a result of the 120-minute treatment, the solid content reduction rate was reduced to 80%, and at this time, brown coloration was observed in the hydrolyzate. Therefore, it is energetically disadvantageous to lengthen the treatment time and the above-mentioned obstacles are recognized. Therefore, in the present invention, the hydrolysis time is 5 minutes to 60 minutes, preferably 10 to 30 minutes. To do.

(Example 2)
Next, the relationship between the hydrolysis temperature and the solid content reduction rate will be described. A bag made of the target polylactic acid material suspended in distilled water at 10 g / L was placed at a predetermined temperature using an autoclave and treated for 30 minutes. Moreover, the hydrolysis effect was represented by the reduction rate of solid content (SS; Suspended Solid) before and after the heat treatment. The measuring method was measured according to the sewer test method (supervised by the Ministry of Construction and the Ministry of Health and Welfare, 1997 edition).

  FIG. 4 shows the relationship between the treatment temperature and the solid content reduction rate according to this experimental result. It can be seen from the figure that the hydrolysis treatment at 100 ° C. has almost no effect at a solid content reduction rate of 5%. It can be seen that the solid content weight of 40% is reduced by the treatment at 120 ° C., and is reduced by 80% by the treatment at 150 ° C. Furthermore, at 170 ° C. or higher, the effect reaches a peak at a solid content reduction rate of 95%. In the treatment at 270 ° C., brown color was observed in the hydrolyzate. Therefore, increasing the treatment temperature is disadvantageous in terms of energy, and the above-mentioned obstacles have been recognized. Therefore, in the present invention, the hydrolysis time is 120 ° C. to 250 ° C., preferably 150 ° C. to 180 ° C. And

(Example 3)
Next, the results of experiments and examinations on the effect of dilution water amount on the hydrolysis treatment of biodegradable plastics using a bag of polylactic acid material will be described. To 10 g of a bag made of the target polylactic acid material, 1 ml, 10 ml, 100 ml, and 1000 ml of distilled water were added and suspended for 30 minutes at 170 ° C. using an autoclave. Moreover, the hydrolysis effect was represented by the reduction rate of solid content (SS; Suspended Solid) before and after the heat treatment. The measuring method was measured according to the sewer test method (supervised by the Ministry of Construction and the Ministry of Health and Welfare, 1997 edition). FIG. 5 shows the relationship between the amount of diluted water added and the solid content reduction rate. Under the condition of adding 1 ml of diluted water, almost no hydrolysis effect was observed. Under the condition where the dilution water was 10 ml, the solid content of 75% decreased and liquefied (hydrolyzed). Furthermore, almost 100% was hydrolyzed under the conditions where the dilution water was 100 ml and 1000 ml. Therefore, for effective hydrolysis, it is necessary to adjust the amount of dilution water added so that the solid content is 50% or less (10 g polylactic acid-based material, 10 ml water in this embodiment).
Example 4
Next, we will describe the results of experiments and examinations on the recycling effect of hydrolyzed biodegradable plastics by methane fermentation. A bag made of the target polylactic acid material suspended in distilled water at 10 g / L was treated at 170 ° C. for 30 minutes using an autoclave. The biodegradability effect was evaluated by biochemical oxygen demand (BOD). The recycling effect was evaluated by biogas (methane 60% to 70%, carbon dioxide 30 to 40%) generated by fermentation with methane bacteria. As specific fermentation conditions, 60 ml of 10,000 mg / L methane bacteria sludge is placed in a 120 ml capacity vial, and there is an untreated biodegradable plastic sample and a hydrolyzed biodegradable plastic sample. Then, lactic acid and acetic acid were added at a load of 1 kg / sample / m ³ , and biogas generated at 55 ° C. was quantified for 2 weeks. The results are shown in Table 1.

注１） バイオガスはメタン菌によって発生したメタン、二酸化炭素、水素などのガスの総量であり、おおよそ６５％程度がメタンと考えられる。

Note 1) Biogas is the total amount of methane, carbon dioxide, hydrogen and other gases generated by methane bacteria, and about 65% is considered to be methane.

  From Table 1, it can be seen that the untreated sample has a BOD of 20 mg / L and almost no biodegradability. In addition, the amount of biogas generated by methane fermentation is as low as 0.01 L / g · sample.

  On the other hand, when the hydrolysis treatment according to the present invention is performed, the BOD value becomes 6550 mg / L and it is understood that biodegradability is improved. In addition, the amount of biogas generated by the methane fermentation per target sample weight was also 0.56 L / g · sample. This figure is consistent with the amount of biogas generated from methane fermentation of organic acids such as acetic acid and lactic acid as a control experiment. Accordingly, it is presumed that an organic acid such as polylactic acid is generated from the polylactic acid-based material by hydrolysis by heat treatment, and the organic acid is converted to biogas by the organic acid.

As described above, it can be seen that biodegradable plastic that was hardly recycled (energy recovery following biogasification) without treatment was recycled almost entirely as biogas by hydrolysis.
(Example 5)
Subsequently, Table 2 shows the results of confirming the effect of hydrolysis on biodegradable plastics other than polylactic acid materials on methane fermentation. The materials used were polysaccharides and polycaprolactones. In the hydrolysis treatment, waste bags made of the respective materials were suspended in distilled water at 10 g / L and treated at 170 ° C. for 30 minutes using an autoclave. The biodegradability evaluation and the recycling effect were in accordance with Example 4. Both materials have low biodegradability and recyclability in an untreated system. On the other hand, biodegradability and recycling effect were improved in the hydrolyzed system. In addition, the amount of biogas generated is almost consistent with the result of the polylactic acid material of Example 4.

注１）多糖類系生分解性プラスチックにはキトサン／セルロース／でんぷん系の材料を使用した。

Note 1) Chitosan / cellulose / starch materials were used for polysaccharide biodegradable plastics.

Example 6
Demonstrates the effects of volume reduction and reduction of discharged waste, and the effect of increasing the amount of biogas generated by bench-scale experiments of methane fermentation of garbage collected and collected in a 40L garbage bag. In the methane fermentation, the collected litter was treated in a 40-liter polylactic acid-based biodegradable plastic garbage bag. After fractionating unsuitable fermentation, it was diluted twice with tap water and charged into the fermenter. A fermenter having a capacity of 1.5 m ³ was used and treated at a fermentation temperature of 55 ° C. for a residence time of 20 days. The organic load was 4.5 kg · organic matter / m ³ · day.

  The specific gravity of the raw garbage was 0.5 kg / L. The weight of one garbage bag was 50 g. The volume of the garbage bag was 1L. The amount of biogas generated from the garbage by methane fermentation was 0.6 L / gdry · garbage. The mixing rate of unsuitable fermentation materials other than garbage bags was 15%. The specific gravity of the unsuitable fermentation product was 0.5 kg / L.

  The experimental results are summarized in Tables 3-5.

  From these tables, it can be seen that the volume reduction effect of the waste is 12% and the weight reduction effect of the waste weight is 1.2%. The effect of increasing the biogas was 0.3%. In the present invention, it is known that the volume reduction of waste is particularly effective.

  According to the present invention, by achieving the above-mentioned technical effects, it can greatly contribute to the improvement of global environmental problems in the waste treatment field and the plastic field, and contribute to the technical progress and industrial development of these important industrial fields. It is possible.

It is process outline | summary figure which shows the recycling process of the organic waste which concerns on typical embodiment of this invention. It is process outline | summary figure which shows the recycling process of the organic waste which concerns on another embodiment of this invention. It is the graph which shows the result of having experimented and investigated the effect of the hydrolysis process which concerns on this invention, and showing the relationship between the processing time using the bag of biodegradable plastics (polylactic acid-type material), and solid content reduction | decrease rate. It is a graph showing the result of experiment and investigation of the effect of the hydrolysis treatment according to the present invention, and showing the relationship between the hydrolysis temperature and the solid content reduction rate using a biodegradable plastic (polylactic acid-based material) bag. . This shows the results of experiments and investigations on the effect of the hydrolysis treatment according to the present invention, and shows the relationship between the amount of diluted water (added amount) using a bag of biodegradable plastic (polylactic acid-based material) and the solid content reduction rate. It is a graph. It is a process outline figure of the recycling process of the conventional organic waste which used methane fermentation technology.

Explanation of symbols

1: Combustible waste 2: Sorting machine 3: Fermentation suitable material 4: Fermentation inappropriate material 5: Adjustment tank 6: Methane fermentation tank 7: Methane gas 8: Digested material 9: Dehydrator 10: Dehydrated residue 11: Dehydrated filtrate 21: Water Decomposition equipment 22: Screen 23: Decomposition product 24: Non-decomposition product 25: Diluted water

Claims (12)

  A hydrolysis step of performing hydrolysis by adding dilution water to organic waste containing biodegradable plastic, a methane fermentation step of performing methane fermentation under anaerobic conditions on the hydrolyzed decomposition product, and A recovery process for recovering methane gas produced by fermentation, and a method for treating organic waste containing biodegradable plastic.   Separation process for separating organic waste containing biodegradable plastic into fermentable material and unsuitable fermented material containing biodegradable plastic, and adding hydrolysis water to the unsuitable fermented material for hydrolysis A biodegradability comprising a decomposition step, a methane fermentation step in which methane fermentation is performed under anaerobic conditions, and a recovery step in which methane gas generated by the fermentation is recovered. A method for treating organic waste containing plastics.   The organic material containing the biodegradable plastic according to claim 1 or 2, comprising a separation step of separating a fermentation unsuitable product remaining from the hydrolyzed decomposition product after the hydrolysis step. Of waste treatment.   Prior to the methane fermentation step, the hydrolyzed decomposition products and / or the adjustment steps for adjusting the concentration of the fermentable material into the methane fermentation step are added. The processing method of the organic waste containing the biodegradable plastic in any one of.   The processing method of the organic waste containing the biodegradable plastic according to any one of claims 1 to 4, wherein the biodegradable plastic is used as a container for organic waste.   The processing method of the organic waste containing the biodegradable plastic according to claim 5, wherein the organic waste container is made of a polyester resin material.   The processing method of the organic waste containing the biodegradable plastic according to any one of claims 1 to 4, wherein the biodegradable plastic is used as a food packaging container.   The temperature of the said hydrolysis process is 120 to 250 degreeC, The processing method of the organic waste containing the biodegradable plastic in any one of Claims 1-7.   The processing method of the organic waste containing the biodegradable plastic according to any one of claims 1 to 8, wherein a treatment time of the hydrolysis step is 5 minutes to 60 minutes.   The biodegradability according to any one of claims 1 to 9, wherein the addition of dilution water to the unsuitable fermentation product in the hydrolysis step is performed such that the solid content is 50% or less. A method for treating organic waste containing plastics.   The processing method of the organic waste containing the biodegradable plastic in any one of Claims 1-10 which uses the dehydrated separation liquid of the digest discharged | emitted at the said methane fermentation process as the dilution water of the said hydrolysis process. . Separation means for separating organic waste mixed with biodegradable plastics into fermentable materials and unsuitable fermentation materials containing biodegradable plastics, and hydrolysis means for adding diluted water to the unsuitable fermentation materials and performing hydrolysis And separation means for separating unsuitable fermentation residue from the hydrolyzed decomposition product, and methane fermentation means for performing methane fermentation of the fermentation suitability and hydrolyzed decomposition product under anaerobic conditions And a recovery means for recovering the methane gas generated by the fermentation, and an organic waste processing apparatus including a biodegradable plastic.

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